Studies will continue elucidating the effects of fetal hormones on the metabolic maturation of fetal lungs during the terminal stages of gestation. Hormonal effects on both fetal lung glycogen metabolism and fatty acid synthesis will be carried out in vivo through injections of hormones directly to rat fetuses and in vitro using organ culture methodology at different stages of gestation in the rat. Studies will also continue identifying the role prostaglandins may play in the etiology of respiratory distress syndrome and hyaline membrane disease. The production of prostaglandins by lung tissue may be altered to hyaline membrane disease. Measurement of these substances, prostaglandins E and F in rat fetal lung tissue during gestation, in incubation medium of organ cultured lung tissue, and in blood and urine from infants suffering from respiratory distress at birth may elucidate whether prostaglandins are causative of or an effect from the pulmonary insufficiency that occurs with hyaline membrane disease and whether an alteration in essential fatty acids may also be a factor in the etiology of hyaline membrane disease. BIBLIOGRAPHIC REFERENCE: Friedman Z and Demers LM: Essential fatty acids, prostaglandins and hyaline membrane disease. Ped Res 11(4): 571, 1977.